This disclosure relates to an image forming apparatus such as a printer, a photocopier, a facsimile, or a multipurpose printer that utilizes an electrophotographic method, and particularly relates to a fixation device of the image forming apparatus.
In an image forming apparatus utilizing an electrophotographic method, a surface of a photosensitive drum is uniformly charged by a charge roller and then subjected to exposure by an exposure device such as a LED head to form an electrostatic latent image corresponding to image information, and a thin layer of toner formed on a development roller is electrostatically attached to the electrostatic latent image to form a toner image. Thereafter, a transfer roller transfers the formed toner image to a sheet fed from a sheet feed device and conveyed by a conveyance belt. Then, a fixation device fuses the toner image and the image is thus formed on the sheet.
As such a fixation device, there is a fixation device using a belt heating method in which a fixation belt formed of an endless belt is heated by a heater and is pressed against a fixation roller by a pressure roller facing the fixation roller to form a nip and the conveyed sheet is nipped in this nip to be heated and pressed to fuse the toner image onto the sheet (see, for example, Japanese Patent Application Publication No. 2014-132369 (paragraphs 0013 to 0016, and FIG. 1))